#include<stdio.h>
#include<cs50.h>
#include<math.h>

double year_population(double start,double end);

int main(void){

    int start,end;
    double time;


    //开始数量得大于9
    do{
        start = get_int("Start Size: ");
    }
    while(start < 9);
    //最终数量也得大于开始数量
    do{
        end = get_int("End Size: ");
    }
    while(end < start);

    time = year_population(start,end);
    printf("Years:%.0f\n",time);
    // printf("%d\n",startSize);
    // printf("%d\n",endSize);

}

double year_population(double start,double end){
    double t = log10(end/start)/log10(13.0/12.0);
    t = floor(t);
    return t;
}


